In recent years, the rapid development of a wide variety of wireless-communication devices has brought about a wave of new antenna technologies. Mobile phones and wireless networks are just a few examples of wireless, multiple frequency, and multi-mode devices that have driven the advancement of antenna technology. Antennas used in current and future wireless-communication devices are expected to have high gain, small physical size, broad bandwidth, versatility, low manufacturing cost, and are capable of embedded installation. These antennas are also expected to satisfy performance requirements over particular operating frequency ranges. For example, fixed-device antennas, such as cellular base-stations and wireless access points, should have high gain and stable radiation coverage over a selected operating frequency range. On the other hand, antennas for mobile wireless devices, such as mobile phones, tablets, and laptop computers, should be efficient in radiation and omni-directional coverage. These antennas are expected to provide impedance matching over selected operating frequency ranges.
However, many antennas that are currently used in wireless-communication devices satisfy the embedded installation and low cost manufacturing requirements but have limited bandwidths. Researchers and engineers in the wireless-communications industry seek antennas that are low cost and capable of embedded installation, but are also able to receive and transmit over broad bandwidths for multiple frequency or multi-mode wireless communication devices and systems.